Mushrooms as protection against radiation in space

The lack of effective radiation shielding is one of the most pressing issues yet to be addressed if humans are to embark on long journeys into deep space. On Earth, the planet’s powerful magnetosphere protects us from the deadliest forms of radiation – those produced by solar flares and galactic cosmic rays from afar that travel through the solar system. Astronauts on the International Space Station, about 408 km above Earth, receive increased levels of radiation, but are close enough to Earth to have some protection, and can stay in orbit for up to a year. The same cannot be said about astronauts who travel further, for example, to the Moon or, someday, to Mars. Future travelers into deep space will need to bring their own defenses with them – or, as suggested in a new article, build them up along the way.

According to articlepublished on BioRxiv on November 4, 2021, a special type of fungus that thrives in high-radiation environments (Cladosporium sphaerospermum) can form a human shield around astronauts in space. The fungus not only blocks radiation, but actually uses it to grow through a process called radio synthesis: it extracts energy from radiation, just as most plants extract energy from sunlight through photosynthesis.

These radiation-loving mushrooms survive on Earth in extreme places, for example, in the zone of the Chernobyl nuclear power plant. They feel just as good in space. In 2019, researchers sent several mushrooms to the ISS, observed how they grew for 30 days, and measured the amount of radiation that passed through them compared to a control sample without mushrooms.

The experiment showed that the radiation level under the 1.7 mm thick layer of fungus was about 2.17% lower than under the control sample. What’s more, the fungus grew about 21% faster than on Earth, meaning that the longer the mission lasts, the greater the fungi’s ability to act as a protective shield for astronauts will be.

It is too early to think about the practical application of these mushrooms in space travel. According to the team’s estimates, in order to reduce the radiation level on Mars to terrestrial ones, the habitat must be covered with a layer of radio-synthesizing mushrooms 2.3 meters thick. The same effect can be achieved by burying the habitat under 3 meters of Martian soil (regolith). However, the possibility of biological solutions to what are often considered engineering problems is a unique approach and can prove fruitful.

In the near future, astronauts will rely on more mundane solutions. In the event of solar flares, contingency plans include shelter among the cargo of the spacecraft: the more mass between astronauts and radiation, the more secure they will be. Artemis 1’s upcoming uncrewed mission due to launch next year, is testing a protective vest designed to minimize the radiation doses received by the wearer.

So far, none of these solutions are perfect. There is still a lot of work to be done to keep future astronauts safe. However, when the time comes, don’t be surprised if part of the solution to the cosmic radiation problem involves sheltering under a thick layer of friendly mushrooms.